I was considering the idea of a personal sensor to warn people that they are physically too close within the recommended distance. It seems some people just don't get it, and an a visual/ audible warning might wake them up. But with my limited, lets say robotic knowledge, the cost of such a device is not practical. I would think a pid (infrared) sensor would be required first to detect a human presence, then something like a proximity sensor would be activated and read for distance( possibly a ping ) while the pid sensor is activated. Once the lower limit of the program on micro has been met for distance, a flashing led and audible signal would be activated. Thus the warning signal being directed at said person within the limit. Of course this would only work in the direction the sensor is directed towards.
So in conclusion it is probably not going to be cost effective enough to make into an actual for sale product. ( not me, possibly someone else? )
Possibly some other experienced people here might have some better practical ideas.
Anyway getting bored, thought it would be interesting discussion.